upd78f0148m1gka1-9eu Renesas Electronics Corporation., upd78f0148m1gka1-9eu Datasheet - Page 469

• Manufacturer Part Number: upd78f0148m1gka1-9eu
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

24.4 Cautions for Power-on-Clear Circuit
voltage (V
release of reset to the start of the operation of the microcontroller can be arbitrarily set by taking the following action.
<Action>
software counter that uses a timer, and then initialize the ports.
• If supply voltage fluctuation is 50 ms or less in vicinity of POC detection voltage
Note 1
In a system where the supply voltage (V
After releasing the reset signal, wait for the supply voltage fluctuation period of each system by means of a
Notes 1.
POC
2.
No
), the system may be repeatedly reset and released from the reset status. In this case, the time from
If reset is generated again during this period, initialization processing is not started.
A flowchart is shown on the next page.
Figure 24-3. Example of Software Processing After Release of Reset (1/2)
50 ms has passed?
Change CPU clock
Check stabilization
Checking cause
(TMIFH1 = 1?)
(set to 50 ms)
of oscillation
of reset
Initialization
processing
Start timer
Reset
Power-on-clear
Yes
Note 2
CHAPTER 24 POWER-ON-CLEAR CIRCUIT
DD
User’s Manual U15947EJ3V1UD
) fluctuates for a certain period in the vicinity of the POC detection
; The internal oscillation clock
;
;
;
;
;
;
The cause of reset (power-on-clear, WDT, LVI, or clock monitor)
can be identified by the RESF register.
8-bit timer H1 can operate with the
Source: f
(f
Check the stabilization of oscillation of the X1 input clock by using the
OSTC register.
Change the CPU clock from the
TMIFH1 = 1: Interrupt request is generated.
Initialization of ports
R
:
Internal oscillation clock
R
(480 kHz (MAX.))/2
frequency)
is set as the CPU clock when the reset signal is generated
7
× compare value 200 = 53 ms
internal oscillation clock
internal oscillation
clock.
to the X1 input clock.
469